I just had to try it a couple days ago. Went over south of Yuma with some friends, got bored and wanted some kind of cultural experience while I was there so I got a hair cut and my teeth cleaned.
The hair cut was a good value as they cut almost all of it off... It will grow back with the appropriate amount of wine consumption.
We have to pay for our own insurance @ over $1,400 a month and do not have a dental plan as part of it. Twice a year I pay $200+ for cleaning in the US. In Mexico I found (or I should maybe say "I was found"), and got them cleaned for $20. It was certainly less sophisticated than at home but they used gloves, tools that came from clean wrapped circumstances, wore masks, had spartan but clean offices, and were maybe a little less gentle. I plan to go back to my regular dentist for the next one and see what they think.
I did hear several stories about the positive aspects of dental service over there though (albeit second hand and from those that were not so serendipitous as I and did some home work / reference work prior to having any work done).
There are lots of dental services there but again all the positive info I heard was based upon people getting things done by dentists referred to them by others experiences.
My friends are getting their teeth cleaned by a US trained dentist referred to them by others and that they checked out on the one day trip we took with them last week and that dentist was trained in the US. They are paying twice what I did, $40.00
Another dentist told an acquaintance; he paid $200 a year for his college, has no malpractice insurance, paid a fraction of what the US dentists have to pay for the German equipment due to import duties, and thus does not have as big of a nut to crack to make a profit. Same general circumstances goes for all the generic drugs there.